Multifunctional smart hydrogels are used for tissue engineering, drug delivery and cancer therapy.

The aim of this research was to prepare a novel sponge-like porous hydrogel scaffold based on human-like collagen (HLC) that could be applied in cartilage tissue regeneration. In this study, bovine serum albumin (BSA) was used as a porogen to prepare the porous hydrogel, which had not been previously reported. Glutamine transaminase (TGase) was used as the cross-linker of the hydrogel, because it could catalyze the cross-linking of BSA. During the crosslinking process, BSA and HLC were mixed together, which affected the cross-linking of HLC. When the cross-linking was completed, the non-crosslinked section formed pores. The microstructure, porosity, swelling properties, and compressive properties of the hydrogel were studied. The results showed that the pore size of the hydrogel was between 100 and 300 μm, the porosity reached up to 93.43%, and the hydrogel had rapid water absorption and suitable mechanical properties. Finally, we applied the hydrogel to cartilage tissue engineering through in vitro and in vivo research. The in vitro cell experiments suggested that the hydrogel could promote the proliferation and adhesion of chondrocytes, and in vivo transplantation of the hydrogel could enhance the repair of cartilage. In general, the hydrogel is promising as a tissue engineering scaffold for cartilage.

Hydrogel-based wound dressings provide a cooling sensation, a moist environment, and act as a barrier to microbes for wounds. In this study, a series of soft, flexible, porous non-stick hydrogel dressings were prepared through the simple repeated freeze-thawing of a poly(vinyl alcohol), human-like collagen (or and carboxymethyl chitosan) mixed solution rather than chemical cross-linking and Tween80 was added as pore-forming agent for cutaneous wound healing. Some of their physical and chemical properties were characterized. Interestingly, hydrogel PVA-HLC-T80 and PVA-HLC-CS-T80 presented excellent swelling ratios, bacterial barrier activity, moisture vapor permeability, hemostasis activity and biocompatibility. Furthermore, in vivo evaluation of the healing capacity of these two hydrogels was checked by creating a full-thickness wound defect (1.3 cm × 1.3 cm) in rabbit. Macroscopic observation and subsequent hematoxylin eosin staining (H&E) staining and transmission electron microscopy (TEM) analysis at regular time intervals for 18 days revealed that the hydrogels significantly enhanced wound healing by reducing inflammation, promoting granulation tissue formation, collagen deposition and accelerating re-epithelialization. Taken together, the obtained data strongly encourage the use of these multifunctional hydrogels for skin wound dressings.

The ability of four gel-forming copolymers to act as in situ dermal fillers in plastic and reconstruction surgery was studied. The four hydrogels, which were based on chitosan (CS), included CS/β-GP (β-sodium glycerophosphate), CS–HLC (human-like collagen)/β-GP, CS–AC (animal-derived collagen)/β-GP and CS–Gelatin/β-GP. The potential of the hydrogels as tissue engineering scaffolds was explored by an MTT test and an in vitro degradation assay. The interior morphologies of these hydrogels were also characterized before and after degradation. Histocompatibility in vivo was evaluated by hematoxylin and eosin (H&E) staining, immunohistochemical analysis and transmission electron microscopy (TEM). An MTT assay showed that the CS–HLC/β-GP hydrogel was less cytotoxic and could promote marrow stromal cell (MSC) proliferation better than other hydrogels. Data from an in vitro degradation test showed that the CS–HLC/β-GP hydrogel had a longer degradation time and led to a lower weight loss than the other hydrogels. Furthermore, the CS–HLC/β-GP hydrogel rapidly formed a stable gel that maintained its integrity even after 6 weeks in vivo. From TEM, there were found to be a large quantity of macrophages, fibroblasts, fibrocytes, lymphocytes and capillaries in the CS–AC/β-GP and CS–Gelatin/β-GP hydrogels, whilst levels in the CS–HLC/β-GP hydrogel were small. Furthermore, abnormalities of cell morphology were observed in the CS–AC/β-GP and CS–Gelatin/β-GP hydrogels whereas cell morphology in the CS–HLC/β-GP hydrogel was regular. Therefore, the CS–HLC/β-GP hydrogel, with good cytocompatibility and histocompatibility, is suitable for soft tissue defect filling, such as skin patches, wrinkles, and tissue cavities formed by surgery.